Field of the Invention and Related Art Statement
The present invention relates to an apparatus for recording and/or reproducing information on and/or from an optical record medium such as optical card, optical disc and opto-magnetic disc.
In a known recording and reproducing apparatus using an optical card, a so-called seek operation is carried out in the following manner. A distance between a track on which a reading or writing light spot is made incident and a track on which the light spot is to be made incident upon next is derived by reading an address of the former track and an address of the latter desired track. Then, a head carriage on which an optical pick-up for projecting the focused light beam onto the optical card is installed is moved in a direction substantially perpendicular to a track direction in which the tracks extend in accordance with the thus derived distance. An amount of the movement of the head carriage is detected with the aid of a scale and a position of the head carriage. After the head carriage has been moved over the desired distance, the head carriage is stopped and then the tracking operation is started to effect the track-on and an address recorded in the relevant track is read out. When the read out track address is identical with the address of the desired track, the seek operation is finished. In the optical card, the distance between tracks is rather high, so that the possibility that the light spot is made incident upon the desired track is rather high. However, sometimes the light spot is not made incident on the desired track. When the read out track address is not identical with that of the desired track, the light spot is then moved in forward or backward direction depending on a distance between the relevant track and the desired track. Usually this track jump is performed by moving an objective lens for projecting the light spot. After the light spot has been jumped over the desired number of tracks, an address of a track on which the light beam is made incident is read out and is compared with the address of the desired track. When these addresses are identical with each other, the seek operation is finished.
In Japanese Patent Publication No. 62-20611, there is described a known information recording and reproducing apparatus using an optical disc. In the optical disc, the distance between successive tracks is very small with respect to the pitch of the scale, and therefore the light spot could not be made incident upon the desired track only by moving the head carriage. In this known apparatus the seek operation is carried out by effecting a rough positioning of the optical head with respect to a desired track with the aid of the scale and then a fine positioning is performed by moving the light spot in accordance with a difference between the address of the desired track and a read out address of a track on which the light spot is made incident.
In the above mentioned known apparatus for recording and/or reproducing information on and/from the optical card, after the head carriage is moved toward the desired track and is stopped thereat on the basis of the scale, the tracking operation is initiated and the light spot is made incident upon the relevant track by means of a tracking control. However, the driving portion of the head carriage is not constructed completely separated from the record medium supporting portion, and therefore the record medium is vibrated with respect to the head carriage due to the repelling action of the movement of the head carriage. Therefore, when the tracking operation is initiated immediately after the movement of the head carriage is stopped, the tracking operation could not be effected precisely and the light beam might not be projected on the desired track. Then, it is necessary to effect the track jump in order to made incident the light spot on the desired track. In this manner, in the known apparatus the seek operation could not be performed within a short time and the access time becomes long.